Problem: Subtract. $\dfrac{9}{4} - \dfrac{5}{10} = $
Answer: Before we can subtract our fractions, they need to have the same denominator. $\dfrac{9}{4}$ $\dfrac{5}{10}$ $\dfrac{9}{4}-\dfrac{5}{10}$ Let's look at the multiples of each denominator and see which multiples they have in common. Denominator Multiples ${4}$ $4, {8}, 12, 16, \underline{20}$ $10}$ $10, \underline{20}, 30$ The least common denominator is ${20}$. Let's use multiplication to make each fraction have a denominator of $20$. ${\dfrac{9}{4}}=\dfrac{{9} \times {5}}{{4} \times {5}} = {\dfrac{45}{20}}$ $\dfrac{5}{10}}=\dfrac{5} \times 2}{10} \times 2} = {\dfrac10}20}}$ Now, we can subtract ${\dfrac{45}{20}} - \dfrac{10}{20}}$. $\dfrac{45}{20}$ $\dfrac{10}{20}$ $\dfrac{45}{20} - \dfrac{10}{20}$ $=\dfrac{{45}-10}}{20}$ $= \dfrac{35}{20}$ ${\dfrac{9}{4}} - \dfrac{5}{10}} = \dfrac{35}{20}$ We can also write $\dfrac{35}{20}$ as $\dfrac{7}{4}$ or $1\dfrac{3}{4}$.